I would like to make the 3D Model of a hammer do hit, like pull back then forward, i know i have to rotate it on the y axis but i am usure how to say pull it back x amount then fling it forward ...

This is common animation topic and often done in proper tools like blender or 3d max. Yes, you can hard-code/script the animation of a single hammer, but an animation created by an artist in an animation tool will be most likely superior.

if you have a character swinging a hammer, the most common approach is to use skeletal animation, animate the character motion, and place the hammer at the hand (bone) of the character.